The present invention relates to a method for measuring and analyzing particle size distributions, wherein the particles include blood corpuscles, various cells, latex particles or any other fine particles.
The measurement and analysis of blood corpuscles are known in the art, but it is uncommon that they are applied to a clinical diagnosis. This is because of the difficulty and inaccuracy involved in conducting them. However the recent development of a fluid control system, such as sheath flow control system, has enhanced the accuracy of an automatic measuring method of particle size distributions, and has facilitated the application of the method for clinical purposes. At the same time this has aroused people's attention to the importance of analysis of particle size distribution.
One example of the conventional analyses is disclosed in Japanese Patent Unexamined Publication No. 47(1972)-13299. This prior art method is to analyze the particle size distribution of red blood cells, and is characterized by the representation of the distribution area in terms of quartile variable coefficients.
With respect to the particle size distribution of blood platelets it is presumed that the blood platelets are in a log-normal distribution, and then those which are not in agreement with the presumption are considered as abnormal, which is commonly called a `Curve Fit` method. The feature of the first-mentioned prior art method for red blood cells resides in the indication of the width of the distribution on presumption that the particle size distribution of red blood cells is constantly uniform. In addition, the blood corpuscles are readily affected by dirt and dead cells. For these reasons an inaccurate measurement may result. Furthermore, the blood corpuscles unavoidably contain noise components, so that the thresholds are used to count the number of corpuscles. Nevertheless, when a noise component and a corpuscle overlap or two or more corpuscles overlap each other, the resulting measurement may be inaccurate.
The `Curve Fit` method determines the abnormality of blood platelets on presumption that they are in the log-normal distribution but does not represent the degree of abnormality numerically, that is, in an objective manner.
In order to solve the problems pointed out above, The International Committee for Standardization in Haematology (ICSH) issued an official recommendation in 1982, in which the theoretical distribution should be applied to particle size distributions. The Committee also gave a general statement in support of its recommendation.
In spite of these efforts no practical system of measuring and analyzing particle size distributions has yet been accomplished for the clinical uses.
An object of the present invention is overcoming the difficulties pointed out above, and is to provide a system for measuring and analyzing particle size distribution accurately and readily so as to serve practical purposes, such as clinical diagnosis.
Another object of the present invention is to provide a system for measuring and analyzing particle size distribution, the system being carried out in a limited space without employing a large-size instrumental aid.
These objects are achieved by providing a method for measuring and analyzing particle size distribution. The method includes collecting an analyzing particle size distribution of a given sample content from a particle size measuring instrument. An estimated particle size distribution is set up as a theoretical distribution. The next step includes comparing between the analyzing particle size distribution and the estimated particle size distribution so as to determine the difference between the two. Finally, the difference is made a characteristic parameter for classifying the analyzing particle size distribution according to the sample content.
According to other advantageous features of certain preferred embodiments of the invention, after the estimated particle size distribution is set up as a theoretical distribution, the analyzing distribution and the estimated distribution are compared to set up a classifying characteristic parameter representing the difference therebetween. The analyzing particle distribution content is classified according to the sample content depending upon at least one of the characteristic parameter and the type of estimated distribution.
According to other advantageous features of certain preferred embodiments of the invention, a plurality of estimated particle size distributions are used in the comparing step. In certain preferred embodiments, the number of estimated particle size distributions is determined as a function of the analyzing particle size distribution.
According to other advantageous features of certain preferred embodiments of the invention, a method is provided which includes collecting an analyzing particle size distribution from a particle size measuring instrument, and setting up an estimated particle size distribution as a theoretical distribution as a function of the collected analyzing particle size distribution.
According to the other advantageous features of certain preferred embodiments of the invention, the setting up of the estimated particle size distribution includes setting up a logarithm of the frequency of the analyzing particle size distribution, differeniating the logarithm of the frequency of the analyzing particle size distribution, finding a linear portion of the logarithm of the frequency of the analyzing particle size distribution, calculating a mean value and standard deviation from the linear portion and determining the estimated particle size distribution using the calculated mean value and the standard deviation.
Further objects, features and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for the purposes of illustration only, embodiments constructed in accordance with the present invention.